IMO (not IMEducation), taking any club away on or slightly above the plane is the key.

I've been hitting balls into the net since the snow stayed. My swing looks (and feels) much better taking the club back on plane. It also then eliminates my OTT move, adding speed to my swing (75mph 7 iron OTT, vs 90mph without the OTT move.) Obviosly there are compounding factors, as I think an OTT move doesn't allow the hands to release properly (giving up speed through impact.)